**7. Conclusions**

**6. Nutraceutical oligosaccharides products obtained by diluted thermopressurized phosphoric acid treatment of microalgae cell** 

oligosaccharides – confirms the validity of this technology novelty (**Figure 8**).

Our more recent application of the oPA-mediated catalysis of polymeric sugars has been recently published [64]. The hydrolysis substrates, initially, were microalgae cell walls. This is a very convenient approach to be coupled to microalgae whole biomass once extracted with hot organic solvents (e.g., anhydrous ethanol) to preliminary redeem the lipid material for biodiesel production. In fact, our prospection in these so intensively explored marine unicellular microorganism has gone far: the microalgae (*Chlorella vulgaris*) and cyanobacteria or blue-green algae (*Arthrospira platensis*; formerly *Spirulina platensis*) biomasses, coming from photobioreactors or large open bowls installed in the open roof of local steak house were permanently bubbled with the whole but filtered gases and other volatile components of the hot stream arising from the grills and driven to the bottom of photobioreactors and bowls with the help of a fan. Finalizing, the following chromatographic illustration – variable series of

**Figure 7.** Thin-layer chromatography (TLC) monitoring of inulin (poly-D-fructofuranose) by oPA-catalyzed partial or total hydrolysis along 15 min of incubation at 75°C: pH 4 (*left*), pH 3 (*cente*r) and pH 2 (*right*). Revelator: Hot

FOS (Fructo-oligoSaccharides) with degree of polymerization (DP) from 2 till 10. The two spots ahead fructose are HMF (HydroxyMethylFurufuraldeyde) and probably some DFA (DiFructose anhydride) due to acid reversion of free

9:1. The major spot at Rf = 0.8 is free fructose (F´). The multiband profile (*right*) are

**walls**

fructose.

0.5% orcinol in MeOH:H2

258 Sugarcane - Technology and Research

SO4

Great potential is observed in the deconstruction of phytobiomass polysaccharides to its component sugars. Resulting monomers and/or oligomers can be used for the production of a plethora of products, with application to biofuels, food, fine chemicals and other industries. As mentioned before, due to the inherent characteristics of phosphoric acid, it can be used as an advantageous catalyst for the depolymerization of polysaccharides from a great variety of phytobiomass. Pretreatment technology using very diluted phosphoric acid, alone and under moderated thermopressurization for the bioprocessing of a sugarcane and other L(h)C substrates can possess important advantages over the use of mineral/inorganic acids, despite its relatively higher cost when compared to sulfuric acid, for example. We have shown the potential for using phosphoric acid hydrolysates to fermentation processes using different microorganisms, to the production of bioethanol, to increase nutritional value in animal feed, for starch modification, biomass growth and in the production of prebiotic/alternative sweetener (fructo-oligosaccharides). A continuous study in the use diluted phosphoric acid on different biomass could improve strategies that can be further used in industry and biorefinery processes.
